Thermal runaway detection system for battery in enclosure and method of use

Abstract

To provide a fast, reliable, and robust early detection system for detecting thermal runaway in mobile and stationary applications.SOLUTION: A battery thermal runaway detection sensor system for use in a battery enclosure containing one or more batteries includes at least one gas sensor for detecting the exhaust condition of the battery cells and providing a sensed output in real time. A microcontroller determines power management and signal conditioned outputs on the basis of the sensed output from the at least one gas sensor and the concentration of specific battery exhaust gases. A method of using such a sensor system is also described.SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation-in-part of U.S. Application No. 17 / 021,711, filed September 15, 2020, and claims the benefit of U.S. Provisional Application No. 63 / 202,962, filed July 1, 2021, the entire contents of each of which are incorporated herein by reference.

[0002] The present disclosure relates generally to a detection system for detecting battery faults, and more particularly to a detection system for detecting thermal runaway in a battery within an enclosure, such as a battery used in an electric vehicle (FIG. 2(a)) or a stationary battery energy storage system (FIG. 2(b)). The present disclosure also relates to a method of detecting thermal runaway in a battery using such a system. [Background technology]

[0003] As lithium-ion battery technology improves, the energy density of the battery continues to increase, which increases the risk of battery failure. Thermal runaway in lithium-ion batteries is a significant safety issue for electric vehicles. For example, Global Technical Regulation No. 20 proposed by the United Nations on Electric Vehicle Safety (EVS) requires a five-minute advance warning before a dangerous condition caused by thermal runaway occurs.

[0004] Referring to Figures 1(a) and 1(b), thermal runaway in lithium-ion batteries is a process in which exothermic reactions occur within a failed cell that raises the internal temperature, thereby releasing energy that sustains the internal decomposition reactions and increases the temperature until eventual failure of the cell, often with the sudden release of decomposed electrolyte and gaseous products that can result in fire. While modern lithium batteries can be designed to incorporate controlled venting locations within the cell (see Figure 4), the risk of explosion due to thermal runaway remains a risk in most liquid electrolyte lithium-based batteries.

[0005] Returning to Figures 1(a) and 1(b), certain triggers and abuse conditions can destroy or fail a battery, e.g., a lithium-ion battery, which can cause thermal runaway. Thermal runaway can be caused, for example, by an external short circuit, an internal short circuit (particle, dendrite, separate fault, impact / puncture), overcharge, overdischarge, external heating, or overheating (self-heating). As the temperature rises, gas is generated. If heat dissipation occurs faster than heat generation, a safe outcome can be achieved.

[0006] However, if left unchecked, or if heat cannot be dissipated faster than it is generated, it can result in rapid temperature rise, the release of flammable and harmful gases in the exhaust, flames, and possibly explosions. This can be particularly problematic for vehicles with large battery systems, particularly battery electric vehicles and stationary storage devices, as shown in Figure 3, where thermal runaway of a single cell (Figure 4) can lead to a cascade of thermal runaway events that can engulf the entire pack, resulting in a catastrophic fire and the release of harmful gases. While battery packs can be configured to passively accommodate several failed cells and meet EVS regulations, thermal runaway propagation can still occur. Therefore, it is important to detect cells within the pack that are experiencing thermal runaway.

[0007] Sensors have been developed to detect thermal runaway, but simple gas sensors such as hydrocarbon sensors can only detect electrolyte gas concentrations and suffer from substantial drift as well as cross-sensitivity to other gases, resulting in short life spans for thermal runaway detection sensors.

[0008] Therefore, there is a need for a fast, reliable, and robust early detection system for detecting thermal runaway in mobile and stationary applications.

[0009] No admission is made that any reference cited herein constitutes prior art, and applicant expressly reserves the right to challenge the accuracy and pertinence of cited documents and information. Summary of the Invention

[0010] A detection system is disclosed that addresses the challenge of fast and robust thermal runaway detection within a battery enclosure, generally independent of electrochemical structure, cell packaging (cylindrical, prismatic, or pouch), cell size, and battery configuration (series / parallel), by identifying attributes of the initial cell exhaust shared among multiple design types and responding to the exhaust gases of failed cells.

[0011] During thermal runaway decomposition reactions, cells convert substantial cathode and electrolyte materials to gas, expelling the pressurized gas mixture over a time span of several seconds when the failed cell is in a highly charged state (Figure 1(b)). Thermal runaway tests of typical cell chemistries, such as lithium-manganese-cobalt-oxide (NMC), lithium-cobalt-oxide (LCO), and lithium-iron-phosphate (LFP) batteries, have shown the release of several gases, including significant amounts of carbon dioxide and hydrogen (see Figure 5). Carbon dioxide is typically evolved during the oxidation reaction of carbonate solvents, hydrogen is typically released as a product of the reduction of water resulting from the combustion reaction with carbon monoxide and / or free lithium, and methane and ethane compounds are also present from the reduction reaction of electrolyte and ethylene carbonate at the lithiated anode.

[0012] Also disclosed is the use of such a system to detect (e.g., early detection) thermal runaway, thereby helping to prevent cell-to-cell propagation of thermal runaway, for example, originating from a single cell. In one embodiment, cell exhaust is detected. In one embodiment, thermal runaway is detected. In one embodiment, thermal runaway decomposition products are detected.

[0013] In another example of the present disclosure, at least one additional sensor is provided to detect a secondary battery condition and provide real-time information regarding the rate of cell venting and thermal runaway, including pressure or temperature, and the microcontroller provides the rate of thermal runaway based on the information provided by the secondary sensor. The at least one additional sensor can detect pressure or temperature within the battery compartment housing to determine the rate of venting / thermal runaway. A sensor housing can be provided to seal the at least one sensor and the at least one secondary sensor. Outputs from the primary and secondary gas sensors can distinguish between electrolyte leaks and venting / thermal runaway. System software can be embedded in the sensor microcontroller to determine whether a thermal runaway threshold level has been exceeded and send an alarm to the battery management microcontroller or the charging system controller.

[0014] In yet another exemplary embodiment, the threshold level for thermal runaway is selected from the following: (i) a carbon dioxide level above about 10,000 ppm, (ii) a hydrogen level above about 40,000 ppm, (iii) a carbon dioxide level above the lower explosive limit, (iv) a hydrogen level above the lower explosive limit, and (v) any combination thereof. A multi-chip printed circuit board can be provided that is attached to the battery management controller's printed circuit board. A power management system can be provided that enables a high-speed data acquisition mode during charging / discharging of an active battery system and a reduced acquisition rate / lower power mode when the battery system is not charging or discharging. The detection system can send a wake-up command to the main battery system controller upon detection of exhaust / thermal runaway. The sensor system can include multiple gas sensors selected from two or more hydrogen sensors, two or more carbon monoxide sensors, two or more carbon dioxide sensors, and any combination of any of the foregoing for redundancy in safety-critical applications. The detection system can also include a humidity sensor, a pressure sensor, a temperature sensor, or any combination thereof.

[0015] In another exemplary embodiment, a method for detecting a thermal runaway condition of a battery in a battery enclosure is provided. The method includes providing a detection system as described above, measuring and / or analyzing one or more gases emitted from the battery, and determining whether the analyzed gas level is at or above a predetermined threshold level indicative of thermal runaway of the battery. The analyzed gases may include hydrogen, carbon monoxide, carbon dioxide, or any combination thereof.

[0016] This summary is not intended to identify essential features of the claimed subject matter, nor is it intended for use in determining the scope of the claimed subject matter. It is to be understood that both the foregoing general description and the following detailed description are exemplary and intended to provide an overview or framework for understanding the nature and character of the present disclosure. [Brief explanation of the drawings]

[0017] The accompanying drawings are incorporated into and constitute a part of this specification. It should be understood that the drawings illustrate only some examples of the present disclosure, and that other examples or combinations of various examples not specifically illustrated in the drawings may still be within the scope of the present disclosure. The embodiments are described in further detail through the use of the drawings.

[0018] [Figure 1(a)] FIG. 1 is a flow chart showing the progression of thermal runaway. [Figure 1(b)] 1 is a thermal runaway and temperature chart. [Figure 2(a)] This is a typical battery pack for an electric vehicle. [Figure 2(b)] FIG. 1 is a diagram of a typical battery pack in a fixed energy storage enclosure. [Figure 3] 1 shows a battery thermal runaway detector. [Figure 4] A typical battery cell is shown before and after thermal runaway. [Figure 5] FIG. 1 is a diagram of gases released from a thermal runaway event in cells with different electrochemical configurations, namely, LCO / NMC, NMC, and LFP. [Figure 6] 10 is a plot of cascading thermal runaway propagating through the pack enclosure where an initial cell triggered thermal runaway in several adjacent cells. [Figure 7] This plot shows the rise in hydrogen concentration immediately after the initial event, followed by a slight increase in pressure within the enclosure more than one minute after the event as gas expansion exceeded pack-level pumping capacity. [Figure 8] 1 is a plot of the onset of thermal runaway showing a rapid increase in carbon dioxide concentration within the enclosure. [Figure 9] FIG. 1 is a schematic diagram of a thermal runaway management system. DETAILED DESCRIPTION OF THE INVENTION

[0019] In describing the illustrative, non-limiting embodiments illustrated in the drawings, specific terminology will be used for the sake of clarity. However, it is to be understood that the disclosure is not intended to be limited to the specific terminology so selected, and that each specific term includes all technical equivalents that operate in a similar manner to accomplish a similar purpose. Some embodiments have been described for illustrative purposes, and it will be understood that the description and claims are not limited to the illustrated embodiments, and that other embodiments not specifically shown in the drawings may also be within the scope of the disclosure.

[0020] The battery thermal runaway detector is pre-installed in a cavity of a typical battery housing, for example, as shown in FIG. 3. The housing completely encloses one or more battery modules, each of which has one or more battery cells arranged in parallel or series with one another. The battery cells of each module are in electrical communication with adjacent cells, and the battery modules are in electrical communication with each adjacent module. A battery controller is in communication with each battery module and / or battery cell. The battery controller can operate each battery cell directly or through the module, such as by turning the cell on / off or controlling the voltage output of each cell.

[0021] The enclosure protects the battery cells and modules from water and debris, and protects the user and passengers from electrical hazards within the enclosure. The enclosure void volume (the volume of space within the enclosure) can vary from just a few liters to over 200 liters and typically contains air. Battery enclosures typically feature venting capabilities, including single or multiple small openings, that allow pressure equilibration inside and outside the enclosure, preventing strain and damage to the pack. These openings are typically protected by a hydrophobic membrane that allows air exchange but prevents liquid water from entering the enclosure directly. The enclosure may also include a valve or similar device that allows overpressure from thermal runaway to safely vent the enclosure, reducing the risk of explosion and harmful debris.

[0022] 9, a thermal runaway detector or detection system 100 according to one non-limiting exemplary embodiment of the present disclosure is shown. The detection system 100 resides within a battery housing cavity, as in FIG. 3, and includes a primary detector, here a gas detector 110. The detection system 100 also includes a pressure sensor 112, a relative humidity (RH) sensor 114, and / or a temperature sensor 116.

[0023] In one embodiment of any of the detection systems described herein, the primary gas detector 100 includes one or more sensors for the detection of decomposition products formed during thermal runaway.

[0024] For example, in one embodiment of any of the detection systems described herein, the primary gas detector 110 includes one or more sensors, and in one embodiment includes one or more of a CO2 sensor, a carbon monoxide (CO) sensor, an HF sensor, an H2 gas sensor, and / or a water vapor sensor.

[0025] In one embodiment of any of the detection systems described herein, the primary gas detector 110 includes a CO2 sensor, a CO sensor, an HF sensor, an H2 gas sensor, and a water vapor sensor.

[0026] In one embodiment of any of the detection systems described herein, the primary gas detector 110 includes a CO2 sensor, a CO sensor, an HF sensor, and an H2 gas sensor.

[0027] In another embodiment of any of the detection systems described herein, the primary gas detector 110 includes a CO2 sensor, a CO sensor, an H2 gas sensor, and a water vapor sensor.

[0028] In another embodiment of any of the detection systems described herein, the primary gas detector 110 includes a CO2 sensor, a CO sensor, and an H2 gas sensor.

[0029] In another embodiment of any of the detection systems described herein, the primary gas sensor 110 examines the unique physical properties of the sensed gas without chemically interacting with the gas, thereby providing a reliable and robust primary sensor.

[0030] In another embodiment of any of the detection systems described herein, the primary gas detector 110 further includes one or more secondary gas sensors for detection of one or more gases emitted from the cell prior to thermal runaway (e.g., during SEI decomposition and initial cell evacuation of electrolyte gas products).

[0031] For example, in one embodiment of any of the detection systems described herein, the primary gas detector 110 further includes one or more secondary gas sensors for detecting one or more of methane, ethane, oxygen, nitrogen oxides, volatile organic compounds, esters, hydrogen sulfide, sulfur oxides, ammonia, chlorine, propane, ozone, ethanol, hydrocarbons, hydrogen cyanide, flammable gases, combustible gases, toxic gases, corrosive gases, oxidizing gases, and / or reducing gases.

[0032] In another embodiment of any of the detection systems described herein, the primary gas detector 110 detects CH, C2H2, C2H4, C2H6, diethyl carbonate (DEC), dimethyl carbonate (DMC), ethylene carbonate (EC), ethyl methyl carbonate (EMC), C4H 10 , C3H6, C3H8, and / or POF3.

[0033] In one embodiment of any of the detection systems described herein, the gas detector 100 includes one or more primary sensors for detecting decomposition products formed during thermal runaway and one or more secondary gas sensors for detecting one or more gases emitted from the cell prior to thermal runaway (e.g., during initial cell evacuation of decomposition and electrolyte gas products).

[0034] Detectors / sensors 110-116 are positioned around the housing, and any suitable combination of detectors and / or sensors 110-116 may be utilized.

[0035] The thermal runaway detection system 100 also includes a voltage regulator 120 that provides and regulates sufficient power to operate the sensors 110-116, a microcontroller or microprocessor 118, and a communications transceiver 122. The sensor elements 110-116 are electrically connected to the microcontroller 118 within the detection system 100. The microcontroller 118 interprets the sensor outputs from each of the sensors 110-116 and provides the signal conditioning necessary to convert the raw sensor signals into engineering values ​​for each component. The values ​​are then transmitted to the communications transceiver 122, which provides a data stream of sensor information to a battery management system master controller or other electronic monitoring system.

[0036] When used as one of the primary gas sensors 110, the CO2 gas sensor 110 detects carbon dioxide levels within the housing (FIG. 3) and has long-term reliability and a fast response time (less than 6 seconds to record an event). Background concentration levels of carbon dioxide are typically less than 1,000 ppm; during battery cell exhaust conditions, these concentrations can easily exceed 60,000 ppm within the housing, providing a very robust gas signal for detection, as shown in FIG. 8. With exhaust velocities during exhaust often exceeding 200 m / s, diffusion of carbon dioxide within the housing cavity occurs very rapidly, reaching the gas sensor 110 within 2 seconds, regardless of the sensor's proximity to the exhaust cell.

[0037] In one embodiment of any of the detection systems described herein, the primary gas sensor 110 for the detection of CO 2 is an infrared (eg, near-dispersion infrared) spectroscopic sensor.

[0038] For example, in one embodiment of any of the detection systems described herein, the gas sensor 110 provides an output to the processing device 118, which can determine whether the sensed condition exceeds a predetermined threshold or whether there is a rapid change in the sensed condition.

[0039] In one embodiment of any of the detection systems described herein, the predetermined threshold for detection of a carbon dioxide concentration that signals the triggering of a thermal runaway event is greater than about 1,000 ppm, such as greater than about 10,000 ppm, greater than about 20,000 ppm, greater than about 30,000 ppm, greater than about 40,000 ppm, greater than about 50,000 ppm, greater than about 60,000 ppm, or greater than about 75,000 ppm. In one embodiment of any of the detection systems described herein, the predetermined threshold for detection of a carbon dioxide concentration that signals the triggering of a thermal runaway event is greater than about 10,000 ppm.

[0040] Thus, in one embodiment of any of the detection systems described herein, the system indicates that a thermal runaway event has occurred when the concentration of carbon dioxide detected by the sensor is greater than about 1,000 ppm, such as greater than about 10,000 ppm, greater than about 20,000 ppm, greater than about 30,000 ppm, greater than about 40,000 ppm, greater than about 50,000 ppm, greater than about 60,000 ppm, or greater than about 75,000 ppm. In one embodiment of any of the detection systems described herein, the system indicates that a thermal runaway event has occurred when the concentration of carbon dioxide detected by the sensor is greater than about 10,000 ppm.

[0041] Similarly, the background concentration of hydrogen in the atmosphere is typically around 200-300 ppb. Under battery cell exhaust conditions, the hydrogen concentration inside the battery enclosure can easily exceed 140,000 ppm, also providing a robust signal-to-noise ratio for gas detection, as shown in Figure 7.

[0042] In one embodiment of any of the detection systems described herein, the primary gas sensor 110 for the detection of H2 is a thermal conductivity sensor.

[0043] In one embodiment of any of the detection systems described herein, the predetermined threshold for detection of a hydrogen concentration that signals the triggering of a thermal runaway event is greater than about 200 ppb, such as greater than about 300 ppb, greater than about 1 ppm, greater than about 100 ppm, greater than about 1,000 ppm, greater than about 10,000 ppm, greater than about 40,000 ppm, greater than about 50,000 ppm, greater than about 100,000 ppm, or greater than about 150,000 ppm. In one embodiment of any of the detection systems described herein, the predetermined threshold for detection of a hydrogen concentration that signals the triggering of a thermal runaway event is greater than about 40,000 ppm.

[0044] Thus, in one embodiment of any of the detection systems described herein, the system indicates that a thermal runaway event has occurred when the concentration of hydrogen detected by the sensor is greater than 200 ppb, such as greater than about 300 ppb, greater than about 1 ppm, greater than about 100 ppm, greater than about 1,000 ppm, greater than about 10,000 ppm, greater than about 50,000 ppm, greater than about 100,000 ppm, or greater than about 150,000 ppm. In one embodiment of any of the detection systems described herein, the system indicates that a thermal runaway event has occurred when the concentration of hydrogen detected by the sensor is greater than 40,000 ppm.

[0045] In one embodiment of any of the detection systems described herein, the system indicates that a thermal runaway event has occurred when the concentration of hydrogen detected by the sensor exceeds the lower explosive limit (4%).

[0046] In one embodiment of any of the detection systems described herein, the system indicates that a thermal runaway event has occurred when the concentration of CO detected by the sensor exceeds its hazardous limit and / or its lower explosive limit (12.5%).

[0047] The use of thermal conductivity principles for hydrogen and non-dispersive infrared measurements of CO2 primary sensors results in robust, absolute measurement devices with limited cross-sensitivity to other gases, making such devices ideal for this application where there is little or no opportunity to recalibrate or repair the device in the field. This is generally because the measurement principle is chosen based on the inherent physical behavior of these gas molecules, but does not chemically interact with the target gas or other gases in the environment.

[0048] In one embodiment of any of the detection systems described herein, the secondary gas sensor is a MO (e.g., for the detection of hydrocarbons). x or a pellistor-based sensor.

[0049] The pressure sensor 112 detects the gas pressure level within the battery housing cavity. The nominal air pressure within the housing approximates atmospheric pressure. During thermal runaway venting, pressure may rise rapidly if the venting phase is highly energetic, as in the case of a cell at 100% state of charge (SOC) as shown in FIG. 6. However, the initial associated pressure rise can be very low, especially for small cells or cells at much lower states of charge (SOC), as shown in FIG. 8. Depending on the housing venting system, the increase in gas pressure or temperature can provide information about the rate of thermal runaway. The pressure sensor 112 is small, low-cost, low-power, and has a fast time response, but has been shown to provide insufficient data during slow venting events when the battery housing venting system allows trapped gas to escape at a rate that offsets gas production. However, when used to complement the gas sensor 110, the pressure sensor 112 can provide valuable insight into the progression of thermal runaway as it cascades from the initiating cell to adjacent cells within the enclosure, as shown in Figure 6, where a continuous increase in hydrogen gas concentration and accompanying pressure spikes indicates that thermal runaway is progressing to additional cells, leading to cascading failure of the pack.

[0050] Temperature sensor 116 detects the temperature within the enclosure cavity and, like pressure sensor 112, can be used in conjunction with gas sensor 110 to estimate the rate at which thermal runaway is progressing (FIG. 6). The gradual increase in temperature associated with the thermal runaway of each successive cell provides important data in determining whether the reaction has stopped or is progressing at a rate that requires immediate safety action, such as providing protective measures including, but not limited to, the introduction of water or extinguishing agents, active cooling, the introduction of dilution air or nitrogen, and electrical isolation or discharge of the suspect cell.

[0051] In one embodiment, the temperature sensor 116 detects a temperature in the range of about 100°C to about 1200°C, such as about 600°C to about 1000°C.

[0052] A relative humidity sensor 114 can also be used in conjunction with the gas sensor 110 to monitor the humidity within the enclosure cavity and observe a substantial change in water vapor within the enclosure, which would indicate the formation of water vapor due to decomposition reaction products.

[0053] The detection system 100 can be used in a variety of suitable applications. In the embodiment shown in Figures 2(a) and 3, the detection system 100 is implemented in a vehicle having a battery housing, a power distribution unit, and a battery controller and / or a motor control unit (MCU). The battery housing may be comprised of a plurality of battery cells housed within the battery housing.

[0054] Each of the sensors 110-116 outputs a sensed signal to a processing device, such as a microcontroller 118. The microcontroller 118 converts the analog sensor signals to engineering values ​​and transmits the data, such as an alarm signal or the form of an output signal, to the battery management system via a wired or wireless transceiver 122. The microcontroller 118 can also determine whether the values ​​from the sensors 110-116 exceed a critical threshold for that sensor to indicate cell exhaust, as well as provide algorithms to determine whether the sensors 110-116 are operating normally and within specifications. The detection system 100 can utilize redundant sensors 110-116 to meet safety index levels.

[0055] One or more of the sensors 110-116 are positioned in free space within the vehicle's battery enclosure (FIG. 3), such that the sensors 110-116 are in communication (e.g., gas or pressure communication) with the battery and / or air space proximate the battery compartment to receive and detect conditions resulting from battery cell venting. The sensors 110-116 provide outputs to a processing device 118, which can determine whether the sensed condition exceeds a predetermined threshold (i.e., a threshold that, if exceeded, indicates the onset of thermal runaway-based cell venting) or whether there is a rapid change in the sensed condition. The entire system 100, including the sensors 110-116, microcontroller 118, regulator 120, and transceiver 122, can all be contained within a single sensor housing and located in one location within the battery compartment. In another embodiment, the system 100 can be separate devices, each with its own housing, positioned in a separate location within the battery compartment, including surface mounting for the battery management system electronics.

[0056] As shown and described, the detection system addresses the problem of robust detection of thermal runaway in lithium-ion batteries, where outgassing precursors to thermal runaway can occur over time spans of seconds or hours. The detection system measures multiple physical parameters of outgassing events, enabling detection of rapid thermal runaway as well as slower events. The multiplexed detection technique reduces the risk of false positive and false negative errors and provides sufficient redundancy to meet market safety requirements. The system can measure at least hydrogen and / or carbon dioxide concentrations, supplemented with air pressure and / or temperature and humidity within the enclosure.

[0057] In other variations, the detection system can also include hydrocarbon detection of electrolytes containing methane, ester, and ethane gases. During the initial cell evacuation preceding thermal runaway, the vented gases contain H, CO, CO, and hydrocarbons in concentrations sufficient to be detected by individual sensors. By combining these elements into a single sensor platform with signal conditioning and analysis, it is possible to determine with relative certainty that the event is a single cell experiencing thermal runaway, and by simultaneously monitoring the gases, it is possible to determine the difference between a less critical electrolyte leak and a more critical thermal runaway condition. The use of thermal conductivity principles for hydrogen and non-dispersive infrared measurement of the CO sensor results in a robust, absolute measurement device with limited cross-sensitivity to other gases, making such a device ideal for this application, where there is little or no opportunity to recalibrate or repair the device in the field.

[0058] More specifically, referring to FIG. 6 , an exemplary runaway is shown. In this illustrative example, thermal runaway cascades from one cell to an adjacent cell. Starting at T=0, the battery system operates under normal conditions, with the hydrogen level 150, temperature 160, and pressure 170 all normal. At a first time period, T=1, a first single battery cell in a first battery module undergoes thermal runaway. As a result, the battery cell releases gas, here hydrogen. The hydrogen sensor in the gas detector 110 measures the hydrogen level and has a sensed gas level output. The hydrogen sensor transmits the sensed gas level output to the microcontroller 118. Additionally, the pressure sensor 112 detects the pressure and has a sensed pressure output. The pressure sensor then transmits the sensed pressure output to the microcontroller 118. Additionally, the temperature sensor 116 measures the temperature within the enclosure and provides a sensed temperature output. The temperature sensor 116 transmits the sensed temperature output to the microcontroller 118.

[0059] The sensors 110-116 immediately transmit their sensed outputs to the microcontroller 118 in real time without delay or manual intervention. The sensors 110-116 can transmit their sensed outputs to the microcontroller 118 continuously or intermittently at random or predetermined intervals (e.g., several times per second).

[0060] In the exemplary embodiment of FIG. 6, a cascading thermal runaway event is shown propagating through the pack enclosure, with an initiating cell triggering thermal runaway in adjacent cells. Microcontroller 118 receives sensed gas, pressure, and temperature outputs from gas, pressure, and temperature sensors 110, 112, and 116, respectively. At T=1, hydrogen gas level 150 and pressure 170 both spike. However, temperature 160 only increases slightly. Venting within the battery enclosure allows pressure 170 to quickly dissipate and return to normal levels. However, hydrogen is vented more slowly and remains at an elevated level. Based on these conditions and receiving the sensed outputs, microcontroller 118 determines that at least a first battery cell has experienced a thermal runaway event and generates an alarm signal that it sends to the battery controller. In response, the battery controller can take a first response, such as indicating to an operator that service is needed, reducing the voltage requirements of the battery module, or controlling the battery to prevent it from becoming too hot.

[0061] In the exemplary embodiment of FIG. 6 , at T=2, another cell experiences thermal runaway. Here, the microprocessor 118 determines, based on the sensed outputs from the gas sensor 150 and the pressure sensor 160, that there is another spike in gas and pressure, respectively, and that the temperature has again risen slightly. The pressure returns to normal fairly quickly due to the venting condition, but the temperature and hydrogen level continue their rising pattern. Therefore, the microprocessor 118 determines that another thermal runaway event has occurred and sends another alarm signal to the battery controller. The battery controller can continue with the same response or escalate its response by, for example, shortening the alert response time, indicating the need for immediate repair, or by turning off one or more of the battery modules. The microprocessor 118 determines that there are further spikes at T=3, 4. The various levels of gas, temperature, and pressure can vary based on the venting condition and the particular thermal runaway event. For example, following T=4, the pressure may drop when the housing hydrophobic vent fails, but a spike occurs with each successive cell thermal runaway event as additional cells fail within the housing. The microcontroller 118 or battery controller may further determine that there is a cascading pattern of events and may take additional response actions. The response actions may be transmitted from the battery controller to the microcontroller 118 via the transceiver 122, which then controls the operation of the cells and modules.

[0062] Referring to FIG. 7, another exemplary thermal runaway event is shown. Here, system 100 includes gas sensor 110, here a hydrogen sensor, and pressure sensor 112. At T=1, hydrogen concentration 150 rises immediately after the initial pumping, followed by a slight increase in pressure 170 within the enclosure at T=2 (one minute after T=1) when gas expansion exceeds pack-level pumping capacity. Thus, at T=1, microprocessor 118 generates an alert that thermal runaway has begun. The pressure increase at T2 in FIG. 7 illustrates the delayed response of the pressure signal in this example, where hydrogen gas is present above the lower exposure limit at T1, but the pressure does not substantially increase for more than one minute.

[0063] 8, yet another exemplary embodiment is shown, where the gas detector 110 is a carbon dioxide sensor. The plot shows that the carbon dioxide concentration 150 rises rapidly within the enclosure, while the pressure 170 remains the same and the temperature 160 shows a slight increase. At T=2, the microcontroller 118 determines that thermal runaway has occurred and generates and sends an alarm to the battery controller.

[0064] Thus, the microcontroller 118 uses the sensed outputs from the gas, pressure, RH, and / or temperature sensors 110, 112, 114, and 116, respectively, to determine whether a thermal runaway event or other condition exists within the battery enclosure. The microcontroller 118 may base its determination on a single sensed output or a combination of sensed outputs. For example, the microcontroller 118 may determine that thermal runaway is likely occurring based on the presence of a gas spike alone, and then refer to the sensed pressure output and / or the sensed temperature output to determine whether the thermal runaway event is cascading to additional cells throughout the pack by utilizing a combination of gas measurements to determine an initial thermal runaway event and monitoring increases in pressure or temperature to assess the magnitude of the event. High gas concentration levels and a simultaneous increase in temperature or pressure within the pack indicate that countermeasures have not isolated the event to a single cell and generate an alert to escalate the response. For example, the initial alert may be to notify the vehicle owner to bring the vehicle to a facility where repairs can be performed as soon as possible, and the escalating warning may be to notify the vehicle occupants to pull over and exit the vehicle, with the BMS shutting down the vehicle except for the heat exchanger system to slow the process. However, if the temperature and pressure do not increase, the microcontroller 118 may determine that the thermal event has stopped and that a single cell or group of cells has been identified, and will not generate an alert to escalate the response. Thus, in the given example, the alert continues to notify the vehicle owner to have the vehicle repaired.

[0065] Note that a microcontroller 118 is provided to receive the sensed output, determine the spike, and send an alarm to the battery controller via transceiver 122. However, the microcontroller operations may instead be performed by the battery controller itself, and the sensed output may be sent to the battery controller via the transceiver. A response action signal may be sent directly from the battery controller to the cell via transceiver 122.

[0066] Advantages of the detection system 100 include, for example, the use of known, validated, and field-proven sensor technology, leveraging specific combinations of sensors to enable layered detection mechanisms related to the chemical and thermophysical properties of phenomena associated with thermal runaway events. The system requires little customization to suit various xEV enclosure sizes, cell configurations, and electrochemical structures. The system also has a very fast time response (typically 3-5 seconds) for environments where a rapid response with minimal risk of detector leakage or false positives is required to reliably detect thermal runaway. The system is compact and can operate in multiple modes to reduce parasitic power consumption when the battery enclosure is not actively charging or discharging. These modes can be controlled within the sensor assembly 100 using information received from the battery management system: an active mode (either driving or charging) where fast detection is important and power consumption is less critical, or a passive mode where power consumption is critical and the sampling rate can be reduced to reduce device power consumption.

[0067] The systems and methods of the present invention include operations by one or more processing devices, including a microprocessor 118. It should be noted that the processing device may be any suitable device, such as a processor, microprocessor, controller, application-specific integrated circuit (ASIC), etc. The processing device may be used in combination with other suitable components, such as a display, memory or storage device, input device (touch screen), wireless module (for RF, Bluetooth, infrared, WiFi, etc. devices), etc. Information may be stored on computer media, such as a computer hard drive, or any other suitable data storage device located on or capable of communicating with the processing device. The entire process is performed automatically by the processing device and without manual interaction. Thus, unless otherwise indicated, the process may occur substantially in real time without delay or manual action.

[0068] In another aspect, the present disclosure relates to a method for detecting thermal runaway of a battery (e.g., detecting thermal runaway of one or more battery cells) within an enclosure.

[0069] In one embodiment, the method comprises: (i) providing a detection system according to any of the embodiments described herein within a battery housing; (ii) measuring and / or analyzing one or more gases emitted from the battery; and (iii) determining whether the analyzed gas level is at or above a predetermined threshold level indicative of thermal runaway of the battery.

[0070] In one embodiment, the gases analyzed include hydrogen, carbon monoxide, carbon dioxide, or any combination thereof.

[0071] In one embodiment, none of the detection systems and / or methods described herein i) receive a sensor signal, ii) evaluate the sensor signal against a threshold, or iii) generate an alert based on the results of the evaluation, or any combination of the foregoing.

[0072] In another embodiment, none of the detection systems and / or methods described herein monitor ambient gases within an ambient gas environment.

[0073] It will be apparent to one skilled in the art having the benefit of the teachings presented in the foregoing description and the associated drawings that modifications, combinations, subcombinations, and variations can be made without departing from the spirit or scope of the present disclosure. Similarly, the various examples described may be used individually or in combination with other examples. Those skilled in the art will recognize various combinations of examples not specifically described or illustrated herein that are within the scope of the present disclosure. In this regard, it should be understood that the present disclosure is not limited to the specific examples described, and that the examples of the present disclosure are intended to be illustrative, not limiting.

[0074] As used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Similarly, the adjective "another," when used to introduce an element, is intended to mean one or more elements. The terms "comprising," "including," "having," and similar terms are intended to be inclusive so that there may be additional elements other than the listed elements.

[0075] Furthermore, where the methods described above or the method claims below do not explicitly require an order for its steps to be followed, or, in some cases, no order is required based on the description or claim language, no particular order is intended to be inferred. Similarly, if a method claim below does not explicitly recite a step referred to in the description above, it should not be assumed that the claim requires that step.

Claims

1. a primary gas sensor for simultaneously detecting hydrogen, carbon dioxide, and / or carbon monoxide; A thermal runaway detector, wherein the primary gas sensor is configured to provide a single sensed output indicative of a battery cell exhaust condition.

2. The thermal runaway detector of claim 1 , wherein the single sensed output further indicates a thermal runaway and / or a background condition.

3. 10. The thermal runaway detector of claim 1, wherein the sampling rate of the primary gas sensor is variable depending on whether it is in an active mode or a passive mode.

4. 10. The thermal runaway detector of claim 1, wherein the single sensed output indicates an absolute concentration of the detected gas.

5. 10. The thermal runaway detector of claim 1, wherein the single sensed output is indicative of an explosive threshold of a detected gas or combination of gases.

6. 10. The thermal runaway detector of claim 1, wherein the carbon dioxide concentration is sensed by non-dispersive infrared measurement.

7. 10. The thermal runaway detector of claim 1, wherein the hydrogen concentration is sensed by thermal conductivity measurement.

8. The CO concentration is detected by metal oxide measurement. The thermal runaway detector of claim 1 .

9. If hydrogen is detected at a concentration of 300 ppm or greater, or if carbon dioxide is detected at 10,000 ppm or greater, a battery cell vent condition is indicated. The thermal runaway detector of claim 1 .

10. The fuel cell further includes at least one secondary sensor configured to provide at least one additional measurement of a physical property indicative of an evacuation or thermal runaway condition of the cell. The thermal runaway detector of claim 1 .

11. 11. The thermal runaway detector of claim 10, wherein the physical property is at least one selected from the group of temperature, pressure, and concentration of methane, ethane, oxygen, nitrogen oxides, volatile organic compounds, esters, hydrogen sulfide, sulfur oxides, ammonia, chlorine, propane, ozone, ethanol, hydrocarbons, hydrogen cyanide, flammable gases, explosive gases, toxic gases, corrosive gases, oxidizing gases, reducing gases, and combinations thereof.

12. The physical properties measured are CH ４ , C ２ H ２ , C ２ H ４ , C ２ H ６ , diethyl carbonate (DEC), dimethyl carbonate (DMC), ethylene carbonate (EC), ethyl methyl carbonate (EMC), C ４ H １０ , C ３ H ６ , C ３ H ８ , POF ３ 11. The thermal runaway detector of claim 10, wherein the concentration of at least one selected from the group consisting of:

13. 1. A method for detecting a thermal runaway or exhaust event in a battery, comprising: providing a primary gas sensor configured to measure a concentration of hydrogen, carbon dioxide, and / or carbon monoxide; generating gas concentration measurements of hydrogen, carbon dioxide, and / or carbon monoxide; combining the gas concentration measurements into a single sensed output indicative of the battery cell exhaust condition; and outputting a signal of said single sensed output.

14. providing at least one microcontroller operatively connected to the primary gas sensor and configured to receive the single sensed output signal and determine whether the primary gas sensor has exceeded a critical threshold indicative of battery exhaust and / or thermal runaway; The method of claim 13 further comprising:

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